Apparatus for sensing and measuring tension of tow entering a staple fiber cutter

ABSTRACT

Apparatus for sensing and measuring tension of a tow entering a staple fiber cutter, such as the staple fiber cutter disclosed in the Coffin et al., U.S. Pat. No. 3,557,648. The tow describes a circular path as it continuously is guided onto the cutter at various points around the periphery of the cutter to be wrapped therearound. Thus the tow continuously changes direction, thereby generating a force with a constant vertical component and a variable horizontal component. The apparatus senses and measures only the vertical components of force and includes a guide roll located above the cutter and on the axis of the cutter for guiding the tow to the cutter and mounted on a pivotally mounted lever, the axis of the lever lying generally in the same plane as the axis of the guide roll. A transducer bears against the lever to maintain the generally same plane of the two axes and to sense and measure the movement of the lever and hence only the vertical components of force exerted by the tow on the lever.

United States Patent [191 Smith [111 3,834,263 [451 Sept. 10, 1974 APPARATUS FOR SENSING AND MEASURING TENSION OF TOW ENTERING A STAPLE FIBER CUTTER [75] Inventor: Glen C. Smith, Kingsport, Tenn.

[73] Assignee: Eastman Kodak Company,

Rochester, N.Y.

22 Filed: Nov. 30, 1973 21 Appl. No.: 420,491

[56] References Cited UNITED STATES PATENTS 3,557,648 l/l97l Coffin 83/913 X Primary Examiner.l. M. Meister Attorney, Agent, or Firm-Malcolm G. Dunn; Daniel B. Reece, Ill

[57] ABSTRACT Apparatus for sensing and measuring tension of a tow entering a staple fiber cutter, such as the staple fiber cutter disclosed in the Coffin et al., U.S. Pat. No.

3,557,648. The tow describes a circular path as it continuously is guided onto the cutter at various points around the periphery of the cutter to be wrapped therearound. Thus the tow continuously changes direction, thereby generating a force with a constant vertical component and a variable horizontal component. The apparatus senses and measures only the vertical components of force and includes a guide roll located above the cutter and on the axis of the cutter for guiding the tow to the cutter and mounted on a pivotally mounted lever, the axis of the lever lying generally in the same plane as the axis of the guide roll. A transducer bears against the lever to maintain the generally same plane of the two axes and to sense and measure the movement of the lever and hence only the vertical components of force exerted by the tow on the lever.

5 Claims, 5 Drawing Figures APPARATUS FOR SENSING AND MEASURING TENSION OF TOW ENTERING A STAPLE FIBER CUTTER BACKGROUND OF THE INVENTION The present invention is directed to apparatus for sensing and measuring tension of a continuous filament tow entering a staple fiber cutter.

In the Coffin et al., U.S. Pat. No. 3,557,648 is disclosed a staple fiber cutter of the type contemplated in use of the hereindisclosed invention. The cutter is positioned in a horizontal plane and has knives spaced at predetermined intervals around the periphery of the cutter with the edges of the knives positioned in vertical planes and facing radially outwardly of the cutter.

Elongated material, such as continuous length filamentary material in the form of a tow, is fed to and continuously wrapped around the cutter in layers with the innermost layer in touch contact with the plurality of knife edges. A force is applied on the outermost continuously forming layer which causes the innermost layer to be moved inwardly of and past the knife edges, whereupon the two is severed or cut into predetermined lengths of staple fiber. The length of the severed staple fiber depends upon the interval spacing of the knives, number of wraps around the cutter prior to the severing action occurring and the amount of tension of the tow wrapped around the cutter.

The cutter and its knives are stationary while a driven guide moves around the cutter to engage and guide the tow onto the cutter in the aforedescribed layers.

As the elongated material or tow is guided onto the cutter for wrapping therearound, it describes a circular path as it continuously is guided onto the cutter at various points around the periphery of the cutter. The guide for the tow is mounted on a driven member which moves the guide around the cutter radially outwardly from the knife edges. The tow thus continuously changes direction in describing the aforementioned circular path. The continuous change of direction tends to generate a force with a constant vertical component and a variable horizontal component making it difficult to determine and control the tension in the tow wrapped around the cutter in layers.

If the tension should become too high, the tow layers will be prematurely cut completely through and therefore pull out of the cutter. There would thus be no remaining layers wrapped around the cutter by which other tow could be pulled or fed into the cutter. In the cutter disclosed in the Coffin et al patent it is essential that the integrity of the outer layers be maintained to serve as a cushion between the applied force and the knives, and also so that other layers may be wrapped around what was previously the outermost layers until such latter layers move radially inwardly to become the innermost layers to be severed.

Another disadvantage resulting when the tension is too high is that the lengths of the staple fiber being cut will vary, causing undesired, nonuniform staple fiber lengths. If the tension should not be high enough, some fibers may also be cut longer than others.

Still another disadvantage, insufficient tension on the tow being cut into long staple fibers of about 7 /2 inches for carpet fibers may result in some longer than normal length filaments being cut which may cause dye streaking when such longer than normal length staple fibers are subsequently processed on textile equipment and fonned into carpets.

In the cutting of filamentary tow that has been crimped in a prior processing step, if the tension becomes too high when wrapped around a cutter, the crimp may be permanently and undesirably removed from some fibers.

It is essential, therefore, that the tension be continuously monitored so that it may be regulated or controlled in order to obviate such disadvantages as mentioned above.

Further details of the construction of the fiber cutter and its cutting operation may be obtained by reference to the Coffin et al., patent.

SUMMARY OF THE INVENTION The invention, therefore, is an apparatus for sensing and measuring the tension in the tow or the elongated, flexible material entering a staple fiber cutter such as the staple fiber cutter of Coffin et al., U.S. Pat. No.

3,557,648. The tow or flexible material is continuously changing direction upon entering the cutter at different points around its periphery, thereby producing both variable horizontal and constant vertical components of force on the guide roll above the cutter. The apparatus of the invention serves to isolate the horizontal components of force and sense and measure only the vertical components of force.

The fiber cutter, as heretofore mentioned, is of the type disclosed in the Coffin et al patent, wherein the cutter is horizontally disposed in fixed, nonrotating position and the knives mounted on the cutter are positioned in vertical planes at spaced intervals around the cutter with their cutting edges facing radially outwardly of the cutter.

A driven member on the cutter assembly has mounted thereon a guide which moves with the driven member around the fixed, nonrotating cutter outwardly of the knife cutting edges and for the purpose of engaging and guiding the tow or elongated, flexible material onto and around the cutter in wrapped layers. The innermost layer of material, as heretofore mentioned, is positioned in touch contact with the radially outwardly facing cutting edges of the knives on the cutter. Other incoming successive layers form radially outwardly of the innermost layer. Since the tow is engaged and guided by the guide to the cutter wherever the guide happens to be as it is continuously moved around the cutter, the tow thus describes a circular path in a horizontal plane at the point of engagement with the guide.

The circular path or continuously changing direction of the tow produces the variable horizontal and constant vertical tension forces or components of force on the guide roll positioned above the cutter assembly as the tow goes onto the cutter assembly from the guidev roll. The apparatus of the invention comprises the guide roll, the pivotally mounted lever on which the guide roll is mounted, and a transducer assembly which serves (1) to hold the pivotally mounted lever and its mounted guide roll so that the axis of the pivot of the lever and the axis of the guide roll both lie substantially in the same horizontal plane and (2) to sense and measure only the vertical components of force.

It is essential that the guide roll be located on the axis of the cutter above the cutter and that the axis of the guide roll be located horizontally from the axis of the lever pivot so that the axis of the pivot of the lever will absorb all the horizontal components of the forces in the tow and so that the sum of the vertical components of the forces is transferred to the transducer assembly. The transducer must be isolated from the effects of the horizontal components of tow forces on the guide roll because the vector sum of the horizontal forces will vary with the position of the tow in its circular path described at the point of engagement with the guide on the cutter assembly. The sum of the vertical forces, however, is linearly related to tow tension and, with the proper conversions applied, can be used to measure tension.

The transducer may be a mechanical spring device or, preferably, an electrical one that converts mechanical movement of the pivotally mounted lever into electrical signals so that with proper calibration the tension may be read directly from a meter.

The apparatus of the invention may be used in conjunction with a constant speed fiber cutter and feed rolls (not shown) driven by a variable speed motor (not shown) to control tension of the tow to the cutter. A signal from the transducer assembly would be used to control the speed of the feed rolls so as to maintain the tow passing to the cutter at a constant tension.

BRIEF DESCRIPTION OF THE DRAWINGS the guide roll being supported on a pivotally mounted lever or bell crank and located on the axis of the cutter above the cutter, and further illustrating the transducer assembly;

FIG. 2 is an enlarged view in elevation of the bell crank or pivotally mounted lever of FIG. 1 and illustrating the components of forces;

FIG. 3 is a view similar to FIG. 2 but illustrating the pivotal axis for the bell crank at a different position and thus showing the change in the components of force to be measured as a comparison with the forces shown in FIG. 2;

FIG. 4 is an enlarged elevation of another embodiment of a pivotally mounted lever with the guide roll mounted at one end of the lever and the pivot axis of the lever at the opposite end; and

FIG. 5 is an enlarged elevation of still another embodiment of a pivotally mounted lever with the guide roll mounted at one end of the lever and the pivot axis of the lever intermediate the guide roll and the opposite end of the lever.

DESCRIPTION OF THE PREFERRED EMBODIMENT In reference to FIG. 1, the cutter assembly is illustrated in general at showing only the essential elements for an understanding of its operation, and comprises a horizontally positioned cutter 12, knives 14 mounted on the cutter in vertical planes at spaced intervals, a driven member 16 and a guide 18 and a pressure or force applying roll 20 mounted on the driven member. The driven member 16 is rotatably driven by motor 22.

The tow 24 enters the guide roll 26 horizontally from previous processing operations, makes an approximately turn around the guide roll for subsequent movement to the guide 18 on the cutter assembly 10.

The guide roll 26 with its axis 27 lying in a horizontal plane is mounted at one end of arm 28 on the pivotally mounted lever 30; the lever pivots about axis 32; and the other arm 34 of the lever is engaged by the transducer 36 of the transducer assembly 38. The guide roll is located above the cutter and must be on the central axis of the cutter.

As heretofore stated, the transducer may be a me chanical spring device or an electrical device. Preferably, an electrical device would be more suitable for use in conjunction, for example, with a constant speed fiber cutter and feed rolls (not shown), which would be driven by a variable speed motor (not shown). The electrical transducer assembly could be used to control the speed of the feed rolls to maintain constant tension of the tow passing to the fiber cutter. An example of a transducer that may be used is the one produced by Honeywell Test Instruments Division in Denver, Colorado, involving Model UL4 Statham Load Cell Accessory used with their Universal Transducing Cell.

In reference to FIG. 2, the pivotally mounted lever or bell crank 30 has been lifted from the overall apparatus to illustrate the horizontal and vertical components of force acting upon the lever. Point C represents axis 32 about which the lever pivots and which lies in a horizontal plane, and Point D represents the axis 27 of the guide roll 26. Ty represents the vertical component of the force of tow tension on the roll and is proportional to tow tension; T represents the horizontal component of the force of tow tension which varies with the position of guide 18 on the cutter assembly; X represents the moment arm of Ty about Point C; R represents the horizontal component of reaction force at Point C; R represents the vertical component of reaction force at Point C; F represents the force that the transducer exerts on the lever 30; and Y represents the moment arm of F about Point C. The sum of the moments about Point C, therefore, is equal to T (Z moment arm for T T X is equal to FY. However (2) the moment arm for T is equal to zero and thus cannot be illustrated in FIG. 2; therefore zero (0) T X is equal to FY. F is equal to X/Y Ty. F is therefore a function of only Ty andK/Y. X/Y is a constant for a given apparatus; therefore knowing F one can readily determine T which is the vertical component of force sensed and measured by the transducer assembly 38 bearing against the arm 34 of the pivotally mounted lever 30. Since T is proportional to the tension in the tow at all times, one can readily determine the tension in the tow.

FIG. 3 represents the situation where the lever 30' is pivoted about Point C", which is a point at a distance below Point C but in the same vertical plane as Point C. In this example, Point D represents the axis 27 of the guide roll 26 of FIG. 1; T," represents the vertical component of tow tension; T,,' represents the horizontal component of tow tension; X represents the moment arm of T about Point C"; R represents the vertical component of reaction force at Point C"; R represents the horizontal component of the reaction force at Point C; F represents the force that the transducer exerts on the lever 30'; Y represents the moment arm'of F about Point C"; and 2 represents the moment arm of T about Point C". The sum of the moments about Point C", therefore, is equal to Ty X T Z is equal to F Y. F is equal to T." X T,, Z/ Y. F would thus be a function of both the horizontal and vertical components of tow force. If the pivot of the axis of lever were to be located at Point C", it would not be possible to sense and measure only the vertical components of force.

FIG. 4 represents another embodiment of the apparatus of the invention. The pivotally mounted lever is pivoted about a horizontal axis 42 located at one end of the lever, with the guide roll 44 and its axis 45 being located at the opposite end of the lever. The transducer 46 of the transducer assembly 48 bears against the lever at a point intermediate the two ends of the lever. The tow 49 passes over the guide roll 44 to the cutter (not shown) that would be located below the guide roll.

FIG. 5 represents still another embodiment of the apparatus of the invention. The pivotally mounted lever 50 is pivoted about axis 52 located intermediate the guide roll 54 and its axis 55 at one end of the lever and the opposite end of the lever. The transducer 56 of the transducer assembly 58 bears against the lever at a point adjacent the end of the lever opposite the guide roll. The tow 59 passes over the guide roll 54 to the cutter (not shown) that would be located below the guide roll.

The transducer, as heretofore mentioned, converts the mechanical movement of the lever into electrical signals, which in turn may be suitably fed to suitable equipment for acting in response to the signals generated.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

I claim:

1. In an apparatus for cutting elongated, flexible material into predetermined shorter lengths, the apparatus including a horizontally positioned cutter having knives spaced at predetermined intervals around the periphery of the cutter with their edges positioned in vertical planes and facing radially outwardly of the cutter, a driven member movable in a path around the cutter and having a guide mounted thereon for movement therewith for engaging and guiding the elongated material onto and around the cutter for wrapping the material therearound against the knife edges, and wherein the elongated material is guided from above the apparatus to the guide on the movable driven member, the

material thus defining a circular path at the location where the material engages the moving guide as the elongated material changes direction and hence generates variable horizontal and constant verticalcomponents of force in engaging the guide at different locations of the moving guide around the cutter prior to being guided by the guide to the cutter. the invention comprising an apparatus for sensing and measuring the tension of the elongated material being wrapped around the cutter by sensing only the vertical components of force and comprising:

lever means positioned above the cutter and pivotally mounted about a horizontal axis for rotative movement in a vertical plane; said lever means having at one end spaced from its horizontal axis a guide roll located above and on the axis of the cutter for guiding thereover the elongated material to the guide on the driven member below the lever means, the axis of the guide roll extending horizontally and normally lying substantially in the same horizontal plane as the horizontal axis of the lever means; and means bearing against the lever means to generally maintain the guide roll axis in said substantially same horizontal plane and to sense and measure the vertical force exerted against it due to the forces generated by the elongated material as it moves over the guide roll to the cutter and tends to cause a rotative movement of the lever means. 2. In the apparatus as defined in claim 1, and wherein said lever means comprises an arm with the guide roll mounted at one end and the horizontal axis at the opposite end.

3. In the apparatus as defined in claim 1, and wherein said lever means comprises an arm with the guide roll mounted at one end and the horizontal axis intermediate the opposite end of the arm.

4. In the apparatus as defined in claim 1, and wherein said lever means comprises a bell crank pivotally mounted at the juncture of its two arms with the guide roll mounted at the end of one arm and the other arm bearing against the means which generally maintains the guide roll axis in said same horizontal plane.

5. In the apparatus as defined in claim 1, and wherein said means bearing against the lever means to generally maintain the guide roll axis in substantially the same horizontal plane with the pivotal axis of the lever means includes a transducer for converting movement of the lever means into an electrical signal.

P(%-/%%F;0 UNITED STATES PATE T OFFICE CERTIFICATE 0F CORRECTIN PatentxNo. 3,834,263 Dated September'lO, 1974 Inventor(s) Glen C.-

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Column 5 lines 2 and 3, "F' is equal to Tv'X' T 'Z/Y'" should be changed to -F' is equal to Tv'X' T 'Z Signed and sealed this 11th day of March 1975.

(SEAL) Attest:

' c MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks 

1. In an apparatus for cutting elongated, flexible material into predetermined shorter lengths, the apparatus including a horizontally positioned cutter having knives spaced at predetermined intervals around the periphery of the cutter with their edges positioned in vertical planes and facing radially outwardly of the cutter, a driven member movable in a path around the cutter and having a guide mounted thereon for movement therewith for engaging and guiding the elongated material onto and around the cutter for wrapping the material therearound against the knife edges, and wherein the elongated material is guided from above the apparatus to the guide on the movable driven member, the material thus defining a circular path at the location where the material engages the moving guide as the elongated material changes direction and hence generates variable horizontal and constant vertical components of force in engaging the guide at different locations of the moving guide around the cutter prior to being guided by the guide to the cutter, the invention comprising an apparatus for sensing and measuring the tension of the elongated material being wrapped around the cutter by sensing only the vertical components of force and comprising: lever means positioned above the cutter and pivotally mounted about a horizontal axis for rotative movement in a vertical plane; said lever means having at one end spaced from its horizontal axis a guide roll located above and on the axis of the cutter for guiding thereover the elongated material to the guide on the driven member below the lever means, the axis of the guide roll extending horizontally and normally lying substantially in the same horizontal plane as the horizontal axis of the lever means; and means bearing against the lever means to generally maintain the guide roll axis in said substantially same horizontal plane and to sense and measure the vertical force exerted against it due to the forces generated by the elongated material as it moves over the guide roll to the cutter and tends to cause a rotative movement of the lever means.
 2. In the apparatus as defined in claim 1, and wherein said lever means comprises an arm with the guide roll mounted at one end and the horizontal axis at the opposite end.
 3. In the apparatus as defined in claim 1, and wherein said lever means comprises an arm with the guide roll mounted at one end and the horizontal axis intermediate the opposite end of the arm.
 4. In the apparatus as defined in claim 1, and wherein said lever means comprises a bell crank pivotally mounted at the juncture of its two arms with the guide roll mounted at the end of one arm and the other arm bearing against the means which generally maintains the guide roll axis in said same horizontal plane.
 5. In the apparatus as defined in claim 1, and wherein said means bearing against the lever means to generally maintain the guide roll axis in substantially the same horizontal plane with the pivotal axis of the lever mEans includes a transducer for converting movement of the lever means into an electrical signal. 